Composite lap for grinding and polishing machines



April 14, 1964 w. E. DAvls 3,128,580

COMPOSITE LAP FOR GRINDING AND POLISHING MACHINES Filed Jan. 30, 1963 5Sheets-Sheet 1 WALLACE E. Dwls By M Arrv.

COMPOSITE LAP FOR GRINDING AND POLISHING MACHINES W. E. DAVIS April 14,1964 5 Sheets-Sheet 2 Filed Jan. 30, 1965 INVENTOR WALLACE E. DAVIS HKMrrY,

April 14, 1964 w. E. DAvls 3,128,580

COMPOSITE LAP FOR GRINDING AND PoLIsHING MACHINES Filed Jan. 30, 1963 5Sheets-Sheet 5 April 14, 1964 w. E. DAvls 3,128,580

COMPOSITE LAP FOR GRINDING AND POLISHING MACHINES Filed Jan. 30, 1963 5Sheets-SheetI 4 INVENTOR. WALLAcE E. DAvlS BY/ ATTY.

April 14, 1964 w, E, DMS 3,128,580

COMPOSITE LAP FOR GRINDING AND POLISHING MACHINES Filed Jan. 30, 1963 5Sheets-Sheet 5 Filo 7'3725 '"6 725 113 I 722 70o 723 l 723 INVEN-rorzWALLAeE E. DAVIS nited States The present invention relates to grindingand polishing machines and has particular reference to a novel form ofcomposite diamond lap wherein the coolant liquid may more effectively beapplied to the article or articles undergoing lapping and the resultantsludge more effectively discharged from the surface of the lap.

In United States Patent No. 2,607,174, granted on August 19, 1952, toRalph Lanius and entitled Method of Grinding Eyeglass Lenses, there isshown and described a grinding and polishing machine which is suitablefor carrying out the particular grinding method of such patent. It is tothis general class of machines that the present invention relates andthe composite lap of the present invention is applicable to the machinewhich is shown in the Lanius patent, as well as to various otherso-called lapping machines for performing the same function.

Insofar as the abrasive material which performs the actual cutting,grinding or polishing operation is concerned, rotary laps may be dividedinto two general classes. In one type of lap, the lap body is formed ofclose grained cast iron and a relatively small quantity of abrasivematerial, such as finely divided emery, in suspension in a liquid, suchas water, is continuously applied to the lap surface for effecting theactual removal of material from the article or articles undergoinglapping, this liquid material being distributed over the surface of thelap by a natural spreading operation. In the other type of lap, asexemplified by the machine which is illustrated in the Lanius patent,the abrasive material is in the form of finely divided crushed orfragmented diamonds which are embedded in a metallic or other matrixwith the cutting points of the diamonds protruding outwardly beyond thesurface of the matrix and this protruding relationship being maintainedthroughout the life of the matrix as the embedding material wears away.In the operation of this latter type of lap, a liquid coolant issupplied to the lap surface in relatively large quantity to produce athin film on which the article undergoing lapping is supported or oats,so to speak, with the diamond cutting material projecting through andprotruding above the film surface a predetermined distance as determinedby the particle size. The thickness of the coolant film, as determinedby the character of the coolant, and as related to the particles size,determines the nature of the cutting operation, and when these twofactors are properly correlated, the rate of removal from the article orarticles undergoing lapping is at its maximum consistent with effectivelapping, i.e., without producing surface blemishes, such as grooves orstriations, burn spots, and the like. Broadly stated, laps of the firstmentioned type employ loose or free abrasive particles which may or maynot have a diamond content. Laps of the last mentioned type employdiamond particles which are fixed with respect to the lap surface androtate with the lap about the central axis of rotation. Laps of thefirst mentioned type are usually designed for slow speed rotation andthe liquid material which is applied thereto has but little coolingfunction, it serving merely to distribute the abrasive particles evenlyover the lap surface. Laps of the second mentioned type are usuallydesigned for highspeed rotation and the liquid coolant that is appliedthereto is both for cooling purposes and to prevent surface burns, aswell as to provide the aforementioned film which properly spaces thesurfaces undergoing lapping from the upper face of the diamond-carryingmatrix.

arent ICS The present invention is specifically concerned with laps ofthe fixed particle type as outlined above and it is to be distinguishedfrom laps which employ loose abrasive particles over the wrokingsurfaces thereof since to this class of lap the present invention is notapplicable. It should be further understood that throughout thisspecification and in the following claims the terms lap and lappingrelate to working platens and operations respectively by means of whichmaterial is actually removed from the surfaces undergoing treatment andis carried away by the liquid coolant.

The improved composite lap comprising the present invention has beendesigned for use primarily in connection with the grinding and polishingof articles having spherical or arcuate surfaces, especially lenseswhich are formed of glass or other transparent materials, such asquartz, synthetic plastics and the like, and are used for optical purposes. The invention is, however, capable of other uses and compositelaps constructed in accordance with the principles of the presentinvention may, if desired and with or without modification, be employedVin theV grinding and polishing of articles having planar surfaces, as,for example, piezo electric or quartz oscillator crystals and smallmachine parts, such as the running seal faces of mechanical seals.Irrespective, however, of the particular use to which the presentinvention may be put, the essential features thereof are at all timespreserved.

In connection with a lap of the type briefly outlined above, it has beenfound, particularly where the diamond abrasive is of small mesh ormicron size, that there is a tendency for the surface undergoing lappingto run dry due to the inability of the coolant liquid to enter betweenthe article undergoing lapping and the operative lapping surface of thelap. One reason for this resides in the small entrance area leading tothe space existing between the article and the operative lap surface.Furthermore, the working pressure which is maintained draws the tworunning surfaces together with sufficient force to exclude the entranceof the coolant liquid. For these same reasons, it is difficult todischarge the fine silt-like sludge which is created as a result of thelapping operation from beneath the article.

Another limitation that is attendant upon the construetion and use of aconventional lap resides in the interference which is offered byresistance of the material undergoing lapping to actual stock removalfrom the surface thereof. This resistance restricts and sometimesterminates altogether the free movement of the article undergoinglapping. This latter limitation is prevalent in connection with the useof that class of lapping machines in which the work holder is intendedto allow freedom of movement of the article on the lap surface under theinfluence of frictional forces between the lap surface and the articlesthemselves, while at the same time, the work holder is prevented fromrevolution about the axis of rotation of the lap. In such machines, thework holder to which the article is affixed is usually mounted forlimited universal movement in one sector of the lap area, while at thesame time, itis permitted freedom of rotation about its own axis. It isthus held against revolving about the axis of the lap while the surfaceof the article undergoing lapping is free to seat squarely upon the lap.Due to the higher circumferential speed of the outer regions of the lapthan the circumferential speed of the inner regions of the lap, africtional differential is set up which produces unbalanced forces onthe article tending to cause rotation of the work holder. In the case ofa single article, the same is caused to rotate on the lap, while in thecase of plural articles, the articles are given a localized rotary pathof movement over the rotating lap surface. However, when a high degreeof stock removal is taking place, this freedom of movement of the workholder is restrained, and

since the involved frictional differential is invariably small,amounting to but a few dynes of resultant torque on the work holder, thefree movement of the work holder is retarded appreciably, even to thepoint of its cessation altogether. The net result is the production ofarcuate striations on the surfaces undergoing lapping due to repetitionsencounter with the same diamond or other grit particles which repeattheir paths of movement across the surface being lapped.

The present invention is designed to overcome the above-notedlimitations that are attendant upon the construction and use ofconventional optical and similar laps and it, therefore, contemplatesthe provision of a composite diamond lap which physically is soconstructed as to receive and evenly distribute over the operativesurface thereof the liquid coolant to carry the coolant freely betweenthe opposed running surfaces on the lap and article or articlesundergoing lapping without sacrificing the necessary lapping pressure;and to establish and maintain the necessary coolant film between suchrunning surfaces so that there will be no interference with freedom ofindependent rotation of the work holder, and consequently, of thearticle or articles that are carried thereby.

The provision of a diamond lap which, as stated above, avoids thelimitations of conventional laps constitutes the principal object of theinvention, and in carrying out this object, there is provided a lap bodywhich has the desired lap curvature or configuration and in which theoperative abrasive or cutting surface of the diamond-embedding matrix isdivided into sectors or other segments by a series of intervening radialgrooves, or grooves which have a large component of radial direction.The lap surface is essentially annular in that it is provided with acircular central depression therein so that it has both an inner and anouter periphery with the grooves extending between or spanning thedistance between such peripheries. The depth of the grooves ispreferably, but not necessarily, greater than the thickness of thediamond-embedding matrix so that this matrix is thus divided by thegrooves into individual sectors or segments. The grooves which, in thepreferred form of the invention, are radially disposed, serve severalfunctions, principally among which are the creation of an entryway forthe liquid coolant beneath the face of the article undergoing lapping,as well as for the positive forcing of the liquid coolant between theparticle and the lap surface; the equal distribution of the liquidcoolant over the operative surface of the lap so that there will be nocoolant-starved lap areas; and the bleeding of the space between thearticle and the lap surface to the atmosphere to prevent the creation ofa vacuum therein.

Still further, in carrying out the above-mentioned object, in order moreeffectively to feed the inner ends of the diverging grooves in the lapsurface, the central depression with which the inner ends of the groovescommunicate has its wall bowed outwardly or undercut to provide agenerally circular peripheral pocket within which the liquid coolant maycollect under the influence of centrifugal force and from thence bedistributed to the ends of the grooves, while at the same time beingprevented from creating a spout or fountain at the rim of thedepression, such a phenomenon being prevalent when the wall or thedepression is truly cylindrical.

It has been found that in certain instances it may be desirable torestrict the flow of liquid coolant radially outwardly along the groovesby damming up the ends of the latter, so to speak, thereby causing suchliquid coolant as may flow outwardly in the grooves to be retained underthe article or articles undergoing polishing on the lap surface. Towardthis end, in one modified form of the invention, means are provided atthe outer ends of the grooves for effectively damming them so that thequantity of liquid coolant flung from the lap by centrifugal force willbe restricted. In another modified form of the invention, means areprovided at the inner ends of the grooves for effectively restrictingthe quantity of coolant which may enter these grooves and for thusdiverting some of the liquid coolant issuing from the central depressionto the inter-groove areas of the lap. By such an expedient, the tendencyfor too high a concentration of coolant in the grooves with a consequentdearth of coolant on the intergroove areas of the lap is eliminated. Itis a further object of the invention to provide novel means for thusrestricting the outward flow of coolant and effecting a more evendistribution of the coolant over all areas of the lap than hasheretofore been possible.

It is an ancillary object of the invention to provide a compositediamond lap which, by reason of the greater groove depth as outlinedabove, will permit the diamondcarrying matrix which establishes the lapsurface proper to be used to completion, while at the same timemaintaining throughout its entire useful life the benets afforded by theradial grooves.

With these and other objects and advantages in view, which will morereadily become apparent as the following description ensues, theinvention consists in the novel construction, combination andarrangement of parts shown in the accompanying five sheets of drawingsforming a part of this specification.

In these drawings:

FIG. 1 is a side elevational view, partly in vertical longitudinalsection, of a polishing and grinding machine employing a compositediamond lap constructed in accordance with the principles of the presentinvention and designed for use in producing spherical concave surfaceson an optical lens or the like;

FIG. 2 is an enlarged vertical section of the lap of FIG. 1;

FIG. 3 is a section similar to FIG. 2, but showing the lap beingemployed for multiple lens lapping purposes;

FIG. 4 is a top plan View of the lap of FIG. 2;

FIG. 5 is a sectional view similar to FIG. 2 but showing a slightlymodified form of the invention;

FIG. 6 is a sectional View similar to FIG. 2 but showing a diamond lapdesigned for use in producing spherical convex surfaces on an opticallens or the like;

FIG. 7 is a sectional view similar to FIG. 6 but showing another form ofdiamond lap;

FIG, 8 is a top plan view similar to FIG. 4 but showing a furthermodified form of the invention;

FIG. 9 is a top plan view similar to FIGS. 4 and 8, but showing anothermodified form of the invention;

FIG. l0 is a sectional view similar to FIG. 5 but showing a furthermodified form of lap for producing concave surfaces on an optical lens;

FIG. 11 is a plan view of the lap of FIG. 10; and

FIG. 12 is a sectional view similar to FIG. l0 but showing a modifiedform of lap for producing convex surfaces on an optical lens.

Referring now to the drawings in detail, and in particular to FIG. l, amore or less conventional grinding and polishing machine employing acomposite diamond lap constructed according to the present invention hasbeen designated in its entirety by the reference numeral 10 and involvesin its general organization a base casting I2 of hollow, generallycylindrical design and including a central hub portion I4, an upperhorizontal table portion 16, and an outer cylindrical apron portion 1S.The hub portion I4 serves rotatably tot support a composite diamond lapZtl having an upwardly facing convex lap surface 22. The lap 2i) is ofnovel design and constitutes the subject matter of the presentinvention. It will be described in detail presently after itsenvironment in the machine Itl has been set forth.

The lap 2t) is removably carried on the upper end of a verticallyextending rotatable shaft 24 which is telescopically and slidablymounted within a sleeve 26 and is keyed to the sleeve as at 28 forrotation in unison therewith. The sleeve 26 is rotatable in bearings 29which are supported in the hub I4. The shaft 24 is formed with adepending shank 30 of reduced diameter. The lower end of the shank 30receives thereover an adjusting collar 32. A spring 34 has its lower endseated on the collar 32 and has its upper end bearing against adownwardly facing shoulder 36 on the shaft 24 and serves to urge thelatter, and consequently, the lap, upwardly so that the desired workingpressure between the lap surface 22 and the work may be maintained. Aset screw 38 permits the necessary vertical adjustment of the collar 32.A pulley 40 is mounted on the lower end region of the sleeve 26 and isadapted to be driven by a belt 42 leading from a suitable source ofpower which may be the drive shaft of an electric motor (not shown).

The article which is to be applied to the upwardly facing convex lapsurface 22 is adapted to be positioned in a suitable work holder, suchas the holder shown at t) in FIG. l. The work holder 50 illustratedherein is purely exemplary as various other types of work holders may beemployed. The work holder 50 is designed to accommodate the positioningof a single concavo-convex lens blank 52 with its concave face againstthe lap surface 22 and, accordingly, the underneath face of the holderis provided with a surface 54 (FIG. 3) to which the complementary convexface 56 of the blank 52 is suitably cemented or otherwise adhered.

The work holder 5t) is positioned over the rotating face of the lap andis possessed of a limited degree of universal motion so that it willfollow the lap contour. As shown in FIGS. 1 and 2, the work holder isadapted to be positively rotated independently of the rotationalmovements of the lap while preserving such universal motion.Accordingly, the work holder has a ball and socket connection 60 withthe lower end of a spindle 62 and a driving connection in the form ofengageable driving pins 64 and 66 on the work holder and spindle,respectively, establish this driving connection.

The spindle 62 is rotatably mounted in upper and lower bearings 68 and70 and they are carried in a sleeve '72 which is slidable in a yoke 73.The yoke is longitudinally adjustable in a bracket 74 which is pivotedas at 76 to a foot piece '78. The latter is adjustably mounted as at 89on the table portion 16 for movement toward and away from the axis ofrotation of the lap 20. The upper end of the spindle 62 carries a pulley82 which is adapted to be operatively connected to a belt 34 by means ofwhich the spindle is rotated. The yoke 74 is provided with a threadedbore $6 through which there extends a feed screw 88, the ends of whichare rotatable in the brackets` 75. An operating hand wheel 9i? enablesthe feed screw 88 to be manually rotated to adjust the position of theyoke 74,

and consequently, of the work holder 56 toward and away from the lapsurface. The proper working pressure of the work holder 5t) against thelap may be regulated by means of an adjusting collar 92 and acooperating spring 94.

The arrangement of lapping machine parts thus far described is purelyconventional and no claim is made herein to any novelty associated withthe same. The work holder 50 may be positioned against the lap 20 bymechanism other than that illustrated in FIG. l. The illustratedmechanism maintains the work holder against the lap at a lixed radialdistance from the center of the lap, but it is contemplated thatgyratory or other movements having a radial component of motion may beapplied to hte work holder if desired. Under certain circumstances, itmay be found desirable manually to move the work holder 5) over thesurface of the lap in the manner shown and described in theabove-mentioned patent to Lanius. The present invention is independentof any particular lapping machine or any particular form of work holderor work holder operating mechanism and consists rather in the novel formof lap and in the means whereby the lap surface thereof is fed with aliquid coolant, as will now be described in detail.

Referring now additionally to FIG. 2, the composite lap 20 is in theform of a generally cylindrical body 100 which is formed of a suitablemetal, such as brass, bronze, or the like. The at underneath side 102 ofthe body is provided with a bolt-receiving hole 104 for the receptiontherein of a fastening bolt 106 by means of which the lap may be securedto a suitable adapter 108 having a shank 110 receivable in a socket 112in the upper end of the rotary drive shaft 24 (see FIG. 1). The lap body100 is provided with an upper surface 113 which is commensurate in shapeto the configuration of the surface on the lens ,52 or other articleundergoing lapping. As shown additionally in FIG. 4, the upper surfaceof the lap body 100 is substantially covered with a matrix 114 havingdiamond particles distributed throughout the same. The matrix may beformed of any suitable material and the particles are substantiallyevenly distributed therein, the matrix serving to fix the individualdiamond particles on the lap surface for movement with the lap as thelatter rotates. The hardness and other physical characteristics of thematrix are such that as the matrix wears, the diamond particles areexposed for approximately one-third 'of their over-all height, suchbeing the nature of a lap which will produce optimum results and effectmaximum removal of material from the lens with a minimum of wear on thelap surface. The upper surface 72 of the matrix constitutes the actualoperative lap surface.

The upper surface 113 of the lap 20 is formed with a generallycylindrical coolant-receiving depression or well 116, the side wall ofwhich is undercut as at 118 so as to provide an inwardly extending lip120 which constitutes, in effect, a weir over which the liquid coolantthat is supplied to the well is adapted to ow in a manner and for apurpose that will be made clear presently. The lip region of the well116 communicates with a series of radially disposed linear grooves 122(see particularly FIG. 4) which substantially span the distance betweenthe inner periphery 124 of the annular lap surface 113 and the outerperiphery 125 thereof. The depth of the grooves as shown in FIG. 2 ispreferably, but not necessarily, slightly greater than the thickness ofthe matrix so that these grooves cut completely through the matrix andinto the metal of the lap body 100, thus completely dividing the matrixinto a series of independent sectors which are separated from oneanother by the various grooves 122. The bottoms of the grooves 122 havetheir external outer regions 123 turned upwardly so as to provide, ineffect, dams or restrictions which inhibit the passage of liquid coolantalong the grooves. Such an arrangement prevents inordinate centrifugalilinging of the coolant from the outer ends of the grooves and thusconserves the coolant while at the same time serving to hold an adequatesupply of coolant on the upper surface 113 of the lap.

In order to supply the liquid coolant to the lap surface 113, a supplypipe is arranged to discharge such coolant into the well 116 from abovethe lap. Various types of coolant are suitable for use in connectionwith the present lap and any coolant which is non-oily, nonslippery,non-toxic and non-rusting does not necessitate cleaning of the lensblank 52 after a grinding operation, will not permit filling of thespaces between the exposed portions of the diamond particles at the lapsurface 113, and is chemically stable, may be used. Extremely desirableresults have been obtained by either of the liquid coolant materialswhich are now being marketed by Super-Cut, Inc. of Chicago, Illinois,under the trade designations S5 and S25.

A cylindrical guard or shield 131 is secured by screws 133 to themarginal regions of the table portion 16 to collect the liquid coolantwhich is flung from the periphery of the lap 2i). This coolant flowsthrough a series of small holes 135 in the table portion 16 and iscollected in a drip pan 137 for re-use if desired.

During the grinding of the lens blank 52, the blank is mounted on theunderneath surface 54 of the work holder 50, pitch or other suitableadhesive being applied to the lens and surface to hold the lens inposition. The feed screw 8S is manipulated to bring the lens intooperative grinding relation with respect to the lap 20, after which thedriving belts 42 and 84 are set into motion to drive both the lap andthe work holder in the manner previously described. At the same time,the liquid coolant is fed from the pipe 13th to the interior of the well116.

It is to be noted that the working pressure which is maintained byreason of the springs 34 and 94 maintains the surface 54 of the lens 52undergoing grinding in close proximity to the lap surface 113, thesurface of the lens being maintained slightly spaced from the body ofthe matrix by a thin film of the coolant. Only extremely limitedportions of the upper ends of the diamond particles project through thislm and operate upon the lens for cutting purposes. If the surfacetension of the lm is insufficient to maintain the lens properlysupported, the diamond particles will cut too deeply into the lens andprovide scratches on the latter. If the surface tension is too great,insucient cutting action will take place. The character of the liquidcoolant is thus important. With diamond exposure of the magnitude setforth above and with the proper liquid coolant, a long wearing andeifective lap will be obtained.

The various grooves serve several functions when employed in connectionwith diamond laps of the general character herein described. Principalamong these functions is the carrying of the liquid coolant beneath thesurface of the lens undergoing grinding. Due to the pressure which isexerted by the springs 34 and 94 as described above, especially wherediamonds of small particle size are concerned, for example, particles of270 mesh size, or smaller, the surface 54 undergoing lapping and the lapsurface 113 are relatively close together so that there is notsutiicient entrance-way for the liquid coolant to move into the spacebetween the lap and the lens in the absence of the grooves 122. Thesegrooves serve to carry the coolant beneath the lens surface 54 and thusestablish the necessary supporting lrn for effective grindingoperations, and for prevention of scratches on the lens surface andprevention of surface burns. The radial grooves also constituteconduction channels for proper radial distribution of the liquid coolantover the entire lap surface 113. Since the inner ends of the groovescommunicate through the lip 12) with the wall 116, an equal supply ofliquid coolant will be distributed to each radial groove. The undercutportion 11S of the well 116 provides an annular retaining pocket for thecoolant which is forced therein by the centrifugal force initiated bythe high speed of the lap rotation, and as more liquid is supplied tothe well 116, the coolant passes directly from the well around the lip120 and into the inner ends of the various grooves 122 from whence it iscarried outwardly radially of the lap and distributed evenly over thelap surface as previously described.

Although in FIG. 4 eight of the grooves 122 have been shown with thegrooves extending truly radially of the i lap, it will be understoodthat a greater or lesser number of such grooves may be employed ifdesired. Furthermore, it is not essential, but only preferable, that thegrooves extend truly radially since good results may be obtained wherethe grooves extend between the inner and outer peripheries of the lapsurface 113 in secant fashion. These grooves 122 may be formed bycutting completely through a continuous matrix and into the metal of thelap body 100, or they may be formed by making the matrix in individualsegments and then applying them to the surface of the lap body inslightly spaced relationship, in which case the grooves will be of adepth only equal to the thickness of the matrix. In either event, thegrooves will remain in evidence and be effective until such time as thematrix has been completely used up.

In FIG. 3 the composite lap 2G of FIG. l is shown as being operativelyassociated with the lapping of surfaces on plural lens blanks 152. Thelens holder 156 is similar in its construction to the lens holder Sti ofFIGS. l and 2 and to avoid needless repetition of description, referencenumerals of a higher order, but similar in character, have been appliedto the corresponding parts as between the two lens holders. The holderis of larger over-all size than the holder 50 and its underneath surface154 is designed to have adhered thereto a plurality of the lens blanks152 which may be spaced about the longitudinal axis of the holder. Thesurface 154 overhangs both the inner and outer peripheries of the lapsurface 113 of such an extent that the lens blanks 152, during thegyratory motion that is imparted thereto under the influence of thedriving pins 164 and 166, are caused to sweep over these peripheriesduring the course of their movements. If the driving pins 154 and 166are omitted, a similar gyratory motion will be applied to the lensblanks 22) under the influence of the frictional differential whichexists between the faster moving outer peripheral regions of the lap andthe slower moving inner peripheral regions thereof. It is to be noted inconnection with FIG. 3 that although the holder 15u overhangs the innerperiphery of the lap surface 113 and overlies the well 116, there stillis adequate space for introduction of the liquid coolant into the wellfrom the pipe 130.

In FIG. 5, the composite diamond lap is similar in many respects to thelap 20 of FIGS. 1 to 5, inclusive. Thus, again to avoid needlessrepetition of description, reference numerals of a still higher orderhave been employed as between the corresponding parts. In this latterform of the invention, the bottoms of the radial grooves 222 terminateshort of the outer periphery of the lap body so that the matrix is notcompletely divided into individual sectors. The sectors which arecreated by reason of the grooves 222 remain joined together at the outerperiphery of the lap body by narrow circumferentially extending webs223, these webs constituting restrictions against the free flow ofliquid coolant in a manner similar to the restrictions 123 at the outerends of the grooves 122 of the lap 20.

In FIG. 6, the principles involved by the provisions of the radialgrooves 122 in connection with the lap 20 are applied to a compositediamond lap 320 in which the upper surface 313 thereof is of .concaveconfiguration and is provided with grooves 322. The bottoms of thesegrooves 322 have their extreme inner end regions turned upwardly at 323to provide, in effect, dams or restrictions at the inner ends of thegrooves 322, the restrictions inhibiting but not completely preventingthe entry of liquid coolant into the groove from the well 316. Suchdamming of the inner ends of the grooves prevents overooding of the lapwith the liquid coolant and, in effect, serves a function similar to therestrictions 123. In this form of the invention, the matrix 314 isdivided into individual and separate sectors. The lap 320 is designedfor use in the lapping of convex surfaces on concavo-convex, planoconvexor double convex lenses.

The composite diamond lap 420 of FIG. 7 is substantially the same as thediamond lap of FIG. 6 with the single exception that the radial grooves422 have the bottoms of their outer ends turned upwardly as at 423 toprovide fluid restrictions to inhibit coolant discharge as described inconnection with the diamond lap of FIG. 5. In this form of theinvention, the grooves 422 divide the matrix 414 into individualsectors.

In FIG. 8, a further modied form of the invention is illustrated whereinthe radially diverging grooves 522 are of arcuate extent, while in FIG.9, another modied form of the invention reveals that the grooves 622,instead of extending truly radially as in the case of the laps of FIGS.1 to 7, inclusive, extend in secant fashion between the inner and outerperipheries of the lap. In each of these two views, reference numeralsof a progressively higher order are employed to designate correspondingparts as between the laps of the preceding views and those of FIGS.

t 9 8 and 9, thus again avoiding needless repetition of description. Inboth of these views, the grooves involved terminate short of the outerperiphery of the lap, leaving interconnecting webs between the matrixsectors.

In FIGS. lO and 11, the invention is illustrated in connection with agrooved convex lap for producing concave surfaces on a lens blank orsimilar article, and in which the radial grooves 722 have not only theirouter ends blocked by restrictions 723, but also their inner end regionsblocked by restrictions 725, while in FIG. 12, similar restrictions 825are provided at the inner ends of the radial grooves 822 in a concavelap for producing convex surfaces on a lens blank. In these two forms ofthe invention, the grooves terminate short of the inner and outerperipheries of the laps so as to leave narrow webs between the adjacentmatrix sectors. Repetitious description has again been avoided inconnection with each of these forms of the invention by the use ofreference numerals of a higher order to designate corresponding parts asheretofore explained in connection with the other modified forms of theinvention.

Where any of the forms of the invention employing radial grooves havingrestrictions at either their inner or outer ends or at both ends areconcerned, these restrictions may conveniently be made by commencing thegrooves a slight distance away, on the annular lap surface, from theadjacent periphery of the lap, whether it be the outer periphery thereofor the inner periphery or both. The thus restricted ends of the groovesmay have their bottom regions ared upwardly so as to intersect the lapsurface at the extreme ends of the grooves. The illustration of FIG. 1lis typical of the other instances where restricted grooves are employedand the illustration has not been repeated for all such instances.

Restricting the inner ends of the grooves 722 or 822, as the case maybe, is particularly effective in attaining an even distribution of thecoolant over the entire surface of the lap. It is to be noted that byreason of the restrictions 725 and 825, the upper rims 720 and 820,respectively, of the wells 716 and 718 are truly circular and unbroken.These restricted inner ends form, in effect, weirs which establish aneven ow of the coolant thereover in a radially outward direction so thatin each instance, a horizontally directed unbroken curtain of thecoolant ows radially outwardly from the well and into the grooves, aswell as onto the inner-groove areas of the lap, thus insuring uniformityof distribution of the coolant over the entire lap area. The grooveswill receive some of the coolant and conduct the same radially outwards.However, the function of the grooves is primarily one of scavenging thelap of the products of abrasion. Such coolant as does find its way intothe grooves serves to flush the sludge or products of abrasion along thegrooves under the influence of centrifugal force while the intergroovesurfaces of the lap are supplied with coolant directly from the weirs atthe rim of the well.

The invention is not to be limited to the exact arrangement `of partsshown in the [accompanying drawings or described in this specificationsince various changes in the details `of construction may be resorted towithout departing from the spirit of the invention. For example, thelaps 20, 320, 420, 520, 6120, 720 and S2() shown herein are capable `ofuse in connection with various lapping machines other than the machineherein disclosed. Similarly, the work holders 50 and y150` are useablewith other work-manipulating means, the use of the driving pins beingoptional. Therefore, only insofar as the invention has particularly beenpointed out in the accompanying claims is the same to be limited.

This application is a continuation-in-part of copending patentapplication Serial No. 113,589, tiled by me on May 4, 1961, and entitledComposite Lap for Grinding and Polishing Machines (now abandoned).

Having thus described the invention what I claim as new and desire tosecure by Letters Patent is:

1. In a lapping machine for producing a spherical surface in a lens orthe like, in combination, a rotary diamond lap body having an upwardlypresented annular surface of frusto-spherical contour and shapedconformably to the spherical surface to be produced on the lens, a thinsheet-like matrix of uniform thickness throughout bonded to said surfaceand coextensive therewith, said matrix having diamond particlesdistributed throughout the same, said matrix presenting an annular upperlap surface from which xed `diamond particles project in part outwardlyfor cutting purposes as the lap surface becomes progressively worn, saidlap body and matrix, considered as a whole, being formed with a centralwell having a circular rim which `defines the inner periphery of the lapsurface, said lap surface being formed with a series of equally spaceddiverging grooves which are of substantially equal depth throughout andextend from the inner peripheral region of the lap surface to the outerperipheral region thereof so that they substantially divi-de the matrixinto a series of circumferentially spaced segments, the extreme ends ofthe bottoms of said grooves adjacent to one of the =lap peripheriesbeing provided with fluid restrictions therein, and means for supplyinga liquid coolant to said central well.

2.. In a lapping machine, the combination set forth in claim 1 andwherein the uid restrictions are provided at the ends `of the grooveswhich are adjacent to the inner periphery of the lap.

3. In a lapping machine, the combination set forth in claim 1 andwherein the fluid restrictions are provided at the ends of the grooveswhich are adjacent to the outer periphery of the lap.

4. In a lapping machine, the combination set forth in claim 1 andwherein the grooves are of a depth greater than the thickness of thematrix.

5. `In a lapping machine for producing a spherical surface in a lens orthe like, in combination, a rotary diamond lap body having an upwardlypresented annular surface of frusto-spherical contour and shapedconformably to the spherical surface to be produced on the lens, a thin`sheet-like matrix of uniform thickness throughout bonded to saidsurface and coextensive therewith, said matrix having diamond particlesdistributed throughout the same, said matrix presenting an annular upperlap surf-ace from which xed ldiamond particles project in part outwardlyfor cutting purposes as the lap surface becomes progressively worn, saidlap body and matrix, considered as a whole, being formed with a centralwell having a circular rim which defines the inner periphery of the lapsurface, sa-i-d well being provided with a cylindrical wall surface, thebottom region of which is underout to provide an annular pocket and anoverlying inwardly extending circular lip which terminates in saidcircular rim, said lap surface being formed with a series of equallyspaced diverging grooves which are of substantially equal -depththroughout and extend from the inner peripheral region of the lapsurface to the outer peripheral region thereof so that theysubstantially divide the matrix into a series of circumferentiallyspaced segments, the extreme ends of the bottoms of said groovesadjacent to one lof the -lap peripheries being provided with fluidrestrictions therein, and means for supplying a liquid coolant to saidcentral well.

6. In a lapping machine for producing a spherical surface on a lens orthe like, in combination, a rotary diamond lap body having an upwardlypresented annular surface `of frusto-spherical contour and shapedconformably to the spherical surface to be produced on the lens, a thinsheet-like matrix of uniform thickness throughout bon-ded to saidsurface and coextensive therewith, said matrix having diamond particles`distributed throughout the same, said matrix presenting an annular lapsurface from ywhich xed diamond particles project in part outil. wardlyfor cutting purposes as the lap surface becomes progressively worn, saidlap body and matrix, considered as a whole, being formed with a centralwell having a circular rim which defines the inner periphery of the lapsurface, said well being provided with a cylindrical wall surface, thebottom region of which is undercut to, provide `an annular pocket and anoverlying inwardly extending circular `lip which terminates in saidcircular r1m, said -lap surface being formed with a series of equallyspaced `diverging grooves Which are of substantially equal depththroughout and extend from the inner peripheral region thereof and thussubstantially divide the matrix into a series of circumferentiallyspace-d segments, the extreme ends of the bottoms of said groovesadjacent to both of the lap peripheries being provided with fluidrestrictions therein, and means for supplying a liquid coolant to saidcentral Well.

7. In a lapping machine, a rotary diamond lap comprising a lap bodyhaving an upwardly presented annular surface shaped conformably to thecontour of a surface on an article to be lapped, a matrix of uniformthickness throughout bonded to said surface and coextensive therewith,said matrix having diamond particles distributed throughout the same,said matrix presenting an upper annular lap surface `from Iwhich iixeddiamond particles project in part outwardly for cutting purposes as thelap becomes progressively worn, said llap body and matrix, considered asa whole, being formed with a central coolant-receiving well having acircular rim which denes the inner periphery of the lap surface, saidlap surface having formed therein a series of outwardly diverginggrooves which extend from respective points spaced la slight distanceradially outwards of the inner periphery of the lap surface andterminating adjacent to the outer periphery of the lap surface, saidgrooves serving to :divided the lap surface into a :series ofsubstantially equal and circumferentially spaced matrix sectors,adjacent sectorsrbeing connected together at the inner periphery of thelap by narrow webs which constitute restrictions to the radial ow ofcoolant entering said grooves, and means for supplying a liquid coolantto said central well.

8. In a lapping machine, a rotary diamond lap comprising a lap bodyhaving an upwardly presented annular surface 'shaped conformably to thecontour fof a surface on an article to be lapped, a matrix of uniformthickness throughout bonded to said surface and coextensive therewith,said matrix having diamond particles distributed throughout the same,said matrix presenting an upper annular lap surface from which fixeddiamond particles project in part outwardly Ifor cutting purposes as thelap becomes progressively worn, said lap body and matrix, considered asa whole, being formed with a central coolant-receiving well having acircular rim which vdeiines the inner periphery of the lap surface, saidlap surface having formed therein la series of outwardly diverginggrooves which extend from points adjacent to the inner periphery of thelap surface to respective points spaced a slight distance radiallyinwards of the outer periphery of the lap surface, said grooves servingto divide the 'lap surface vinto a series of substantially equal andcircumferentially spaced matrix sectors, adjacent sectors beingconnected together at the outer periphery .of the lap surface by narrowwebs which constitute restrictions to the radial flow of coolant leavingsaid grooves, and means for supplying a liquid coolant to said centralwell.

9. In a lapping machine, a rotary diamond lap cornprising a lap bodyhaving an upwardly presented annular surface shaped conformably to thecontour of a surface on an article to be lapped, a matrix of uniformthickness throughout bonded to .said surface and coextensive therewith,said matrix having diamond particles distributed throughout the same,said matrix presenting an upper annular lap surface from which -xeddiamond particles project in part outwardly for cutting purposes as thelap becomes progressively worn, said Lap body and matrix, considered asa whole, being formed with a central coolant-receiving well having acircular rim which defines the inner periphery of the lap surface, saidlap surface having formed therein a series of outwardly diverginggrooves which extend from respective points spaced a slight distanceradially outwards of the inner periphery of the lap surface torespective points spaced a slight distance radially inwards of the outerperiphery of the -lap surface,

said grooves serving to divide the lap surface into a series ofsubstantially equal and circumferentially spaced matrix sectors,adjacent sectors being connected together at the inner and outerperipheries of the lap by narrow webs which constitute restrictions tothe radial ow of coolant entering and leaving said grooves, and meansfor supplying a liquid coolant to said central well.

10'. In a llapping machine, the combination set forth in claim 9 andwherein the grooves are -of a depth greater than the thickness of thematrix.

References Cited in the le of this patent UNITED STATES PATENTS 888,129Tone May 19, 19018 2,145,888 Moulton et al. Feb. 7, 1939 2,178,835Hudson Nov. 7, 1939 2,226,506 Van Der Pyl Dec. 24, 1940 2,932,138Fluskey et al. Apr. 12, 1960 FOREIGN PATENTS 980,775 France Jan. 3, 1951

1. IN A LAPPING MACHINE FOR PRODUCING A SPHERICAL SURFACE IN A LENS ORTHE LIKE, IN COMBINATION, A ROTARY DIAMOND LAP BODY HAVING AN UPWARDLYPRESENTED ANNULAR SURFACE OF FRUSTO-SPHERICAL CONTOUR AND SHAPEDCONFORMABLY TO THE SPHERICAL SURFACE TO BE PRODUCED ON THE LENS, A THINSHEET-LIKE MATRIX OF UNIFORM THICKNESS THROUGHOUT BONDED TO SAID SURFACEAND COEXTENSIVE THEREWITH, SAID MATRIX HAVING DIAMOND PARTICLESDISTRIBUTED THROUGHOUT THE SAME, SAID MATRIX PRESENTING AN ANNULAR UPPERLAP SURFACE FROM WHICH FIXED DIAMOND PARTICLES PROJECT IN PART OUTWARDLYFOR CUTTING PURPOSES AS THE LAP SURFACE BECOMES PROGRESSIVELY WORN, SAIDLAP BODY AND MATRIX, CONSIDERED AS A WHOLE, BEING FORMED WITH A CENTRALWELL HAVING A CIRCULAR RIM WHICH DEFINES THE INNER PERIPHERY OF THE LAPSURFACE, SAID LAP SURFACE BEING FORMED WITH A SERIES OF EQUALLY SPACEDDIVERGING GROOVES WHICH ARE OF SUBSTANTIALLY EQUAL DEPTH THROUGHOUT ANDEXTEND FROM THE INNER PERIPHERAL REGION OF THE LAP SURFACE TO THE OUTERPERIPHERAL REGION THEREOF SO THAT THEY SUBSTANTIALLY DIVIDE THE MATRIXINTO A SERIES OF CIRCUMFERENTIALLY SPACED SEGMENTS, THE EXTREME ENDS OFTHE BOTTOMS OF SAID GROOVES ADJACENT TO ONE OF THE LAP PERIPHERIES BEINGPROVIDED WITH FLUID RESTRICTIONS THEREIN, AND MEANS FOR SUPPLYING ALIQUID COOLANT TO SAID CENTRAL WELL.